A brief introduction to the concept of friendship serves to underscore its importance for Eisenhower and in particular to his empathetic tendency and his approach to collaboration. Aristotle, whose definition of friendship is probably the best known, distinguished between the utility and the pleasure of friendship, and between each of them and virtue. The former two are fleeting, imperfect and often accidental; the third, based on character, is complete.

Yet, in digging deeper, the concept appears more complex and contentious. Is friendship more a phenomenon of the self or of society? Can it be all at once a basic necessity of human life, a rarefied luxury and an ethical imperative? How much of it is selfish, and how much altruistic? How much of its existence is prima facie, and how much is cultivated and matured, or, to suggest a different, harder metaphor, forged?

It may suffice to take the first point as a known and obvious fact. Friendship can feature, and appeal to, a number of qualities ranging across several types of affection, but they are often harder to distinguish in practice than in theory. Although the nature and scope of affection and value may differ, as do the means for expressing them, all involve some measure of trust, admiration, intimacy and respect. Yet some friendships can be simple, straightforward and durable on their own. Those tend to lack a qualifying, functional modifier, such as political friendship, business friendship, tennis friendship and so on. Among the more interesting of these are group friendships. They can resemble surrogate families with all the drama and pathologies that families bring. They go by several names in history: circle, set, cabal, club, gang, cabinet. They usually have a leader or a center of gravity and a structure: a hub with spokes, a collection of couples or a set of concentric circles, for not all members of the group, team or family are equally close. Like friendship between individuals, a group of friends generally needs constant tending, perhaps even more so. With time and in some cases, however, it may be even more durable than an individual friendship, because the members of the group, and their separate need for partnership, even solidarity, reinforce one another and check the natural tendency to part ways, or to seek alternative associations.